On 25 May, 20:08, "BruceB" wrote:
On earthing conductor size for TT....
See table 4.2, page 29 in the latest OSG
(Cu and Zs not 1ohm)

Buried
* Unprotected *25mm2
* Protected against corrosion *16mm2
* Protected against corrosion and mechanical damage *2.5mm2

Not buried
* Unprotected *4mm2
* Protected against corrosion *4mm2
* Protected against corrosion and mechanical damage *2.5mm2

The values have not changed from 16th to 17th.

Regards
Bruce

Thanks Bruce and Tim - I need to put a secondary TT earth at my garage/
workshop and was a bit gobsmacked about the cable size Andy Wade
mentioned. My house TT earth was installed by the local board aver 30
years and in all likelihoods needs inspection and probable upgrading -
note to self must do this !!

Rob